Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include<bits/stdc++.h>
using namespace std;


int dx[]={1,-1,0,0},dy[]={0,0,-1,1};
char S[1000][1000];
int vis[1000][1000];

int main(){
	int h,w,sum=0,ans=1e9;
	cin >> h >> w;
	for(int i=0;i<h;i++){
		for(int j=0;j<w;j++){
			cin >> S[i][j];
			if(S[i][j]=='.') sum++;
		}
	}
	sum--;
	
	queue<pair<int,int>> q;
	queue<int> q2;
	q.push(make_pair(0,0));
	q2.push(0);
	vis[0][0]=1;
	while(!q.empty()){
		int x=q.front().first,y=q.front().second,z=q2.front();
		q.pop();
		q2.pop();
		if(x==h-1&&y==w-1){
			ans=z;
			break;
		}
		for(int i=0;i<4;i++){
			int xx=x+dx[i],yy=y+dy[i];
			if(xx>=0&&yy>=0 && xx<h&&yy<w && S[xx][yy]!='#'&&!vis[xx][yy]){
				q.push(make_pair(xx,yy));
				q2.push(z+1);
				vis[xx][yy]=1;
			}
		}
	}
	
	cout << (ans==1e9?-1:sum-ans) << endl;
	return 0;
}